Understanding how genes are expressed at the appropriate times in the appropriate tissues is a central problem in the study of animal development. The long-term objective of this work is to elucidate the mechanisms governing correct developmental expression of genes in animals. By so doing, this work can increase the understanding of normal development in humans, and, by inference, the understanding of clinically significant conditions in which normal development is altered. As a model system, the cis-acting regulatory sequences involved in different patterns of tissue-specific regulation of alcohol dehydrogenase (ADH) genes from Hawaiian Drosophila will be investigated. Specifically, in order to localize and characterize the cis-acting sequences responsible for differences in tissue-specific regulation, hybrid ADH genes will be made between cloned parental ADH genes that show dramatic differences in regulation, and these hybrid genes will be introduced into the chromosones of D. melanogaster by P element-mediated transformation. Then, the tissue-specific production of ADH and ADH mRNA will be analyzed for transformants. Once regulatory sequences are roughly localized, site-directed mutagenesis, followed by introduction of altered genes into D. melanogaster will be used to further localize and characterize these sequences. Last, the interaction of nuclear proteins with regulatory sequences will be investigated.